IgE assay (by RAST, CAP etc)

Purified recombinant pineaple profilin and pineapple extract prepared as follows: Fresh fruits were cut into short pieces and ground in a mortar under liquid nitrogen to a fine powder. This powder was then added to prechilled 4-hyxdroxy-4-methyl-2-pentanone (–20°C, 1:2 wt/vol) in several portions, and the obtained suspension was homogenized with a spinning blade homogenizer. Chilled acetone (–20°C) was added to a final fruit/solvent ratio of 1:5. After the suspension was stored overnight at –20°C, it was filtrated over a suction filter and washed twice with chilled acetone (–20°C) and once with chilled acetone-diethyl ether (1:1, –20°C). The filter residue was lyophilized. One gram of the obtained acetone powder was extracted for 40 minutes at 4°C with 20 mL of PBS (10 mmol/L potassium phosphate and 150 mmol/L NaCl pH7.4). The suspension was centrifuged for 30 minutes at 20,000g, and the supernatant was filtered through a 1.2-µm membrane (Reindl et al. 2002)

IgE protocol:RAST (Baur and Fruhmann, 1979)

EAST, CAP (Reindl et al. 2002).

Number of Patients:

6 workers sensitized to papain and 60 asthmatics workers not exposed to airborne proteases but probably to these as constituents of foods (Baur and Fruhmann, 1979)

Most of the patients complained of intense itching and urticarial rashes, followed by abdominal pain, vomiting and diarrhoea. 18 patients had an urticarial rash and a flushed face. Although none of the patients were severely dehydrated, 20 patients presented with shock. Their peripheral pulse and blood pressure were low or absent suggesting an anaphylactic reaction (Kabir et al. 1993)

IgE cross-reactivity and Polysensitisation

High IgE cross-reactivity between pineapple profilin, birch pollen profilin Bet v 2 and latex profilin Hev b 8 was demonstrated by immunoblot inhibition as well as EAST inhibition experiments. In addition, cross-reactivitiy between pineapple profilin and banana profilin has been demonstrated (Reindl et al. 2002).

There are only few studies on the stability of profilins most of them on celery profilin. Compared to other allergens, profilin is a moderately stable protein, more resistant than Bet v 1 homologues but less stable than lipid transfer proteins or cross-reactive carbohydrate deteminants of glycoprotein allergens. (Scheurer et al. 2004)

Nature of main cross-reacting proteins:

Sequence identity of pineapple profilin with that of many others is high including natural rubber latex (80%), pear (77%), apple (79%), celery (72%), sweet cherry (79%), peanut (78%), birch pollen (71%), timothy grass pollen (77%), tomato profilin. This indicates a very high liklihood of IgE cross-reacting although this has not been demonstrated (Reindl et al. 2002)

Allergen properties & biological function:

Pineapple profilin is thought to be an actin-binding protein of the cytoskeleton (Carlsson et al. 1977).

Allergen purification:The recombinant pineapple profilin has been expressed in E. coli and purified by affinity chromatography using poly-(L)-proline as the solid phase. (Reindl et al. 2002)